EndNote Click (formely Kopernio) is a browser plugin that finds the best available PDF of an academic article while you browse. Behind the scenes EndNote Click will search open databases and (where possible) your university's subscriptions to find the best version of the paper for you.
EndNote Click integrates with library proxies to retrieve research articles from library subscriptions. If your library is supported, EndNote Click will configure this for you automatically. When your subscriptions do not grant you access, EndNote Click will search for an open access alternative from its vast database of open access articles. It indexes a range of additional data sources from which PDFs can be retrieved: